Well monitoring for production of solids

ABSTRACT

A method and apparatus for determining when solid particles are produced with a well fluid by utilizing a conductive means which is immersed in the produced well fluid and which is in a known conductive state, said conductive means being adversely affected as to its conductive state when exposed to solid particles such as sand in the well fluid.

'wmeu mates ratem 1 1 1111 3,753,257

Arnold Aug. 14, 1973 \54l WELL MONITORING FOR PRODUCTION 3,264,561 8/1966 Gustafson 338/13 X "F SQLIDS 3,358,229 12/1967 Collins A A 1 324/ CR 2,735,754 2/1956 Dravnicks 7 324/65 CR Inventor: Thomas Ben Arnold, Dallas,Tex. 3,197,724 7 1965 Marsh 338/13 I Assigneez Atlantic Richfield p y, New 3,342,064 I 9/1967 Blattncr 73/86 York. N.Y. Primary Examiner-John W. Caldwell [22] Ffled' 1972 Assistant Examiner-Daniel Myer [211 App]. No.: 229,885 Attorney- Blucher S. Tharp, Roderick W. Mac- Donald et a1.

[52] US. Cl 340/236, 73/86, 166/66, 324/71 E, 338/13, 340/239 R, 340/240 [51] Int. Cl. 60% 21/00 [57] ABSTRACT [58] Field of Search 340/236, 239 R, 240,

340/243, 256, 269; zoo/61.41; 166/25 D, 66; A method and apparatus for determining when solid /45; 324/65 CR, 71 E; 338/13, 36, 38; Particles are produced with a well fluid by utilizing a 73/28 61 R 194 R 194 E 194 M, 231 My conductive means which is immersed in the produced 49:3 86 23/230 C 254 C well fluid and which is in a known conductive state,

' said conductive means being adversely affected as to its [56] Reerences Cited conductive state when exposed to solid particles such U ED STATES PATENTS as sand in the well fluid.

2,993,366 7/1961 Birkncss 73/86 21 Claims, 3 Drawing Figures Patented Aug. 14, 1973 FIG. 2

WELL MONITORING FOR PRODUCTION OF SOLIDS BACKGROUND OF THE INVENTION In various parts of the world if some wells are produced at too high a flow rate, the produced well fluid will contain solid particles such as sand, clay, and the like, and the production of too much solids can raise a safety question since the solids can erode vital parts in a wellhead or other producing apparatus which in turn could make the well more subject to a blowout. Thus, it is important to know at what flow rates a well will or will not produce solid particles.

This becomes even more important if the well is allowed to be produced at its maximum rate. In such an event, the maximum flow rate would be set at a value which is just below that rate at which the well produces minimum solids along with the well fluid.

Thus, it is important to be able to determine what the threshhold flow rate is above which solid particles will be produced with the well fluid and to be able to monitor a producing well continually in a manner which will warn the operator if the well should suddenly start producing solid particles insubstantial amounts. A well can suddenly start producing sand, for example, when it has not in the past simply because a portion of the wellbore wall suddenly sloughs off into the wellbore and is washed out of the wellbore by the produced well fluid.

SUMMARY OF THE INVENTION According to this invention there is provided a method for determining when solid particles are being produced along with the well fluid.

The apparatus according to this invention comprises a wellhead means, at least one production outlet pipe operably connected to the wellhead, and at leaast one conducting means in one or more or all of the outlet pipes connected to the wellhead, means for establishing a known conductive state such as electrical current or pressure or the like in the conductive means, and sensing means operably connected to the conductor means to sense any change in the conductive state from that which is known, the change in the conductive state being due to erosion of the conductor means by impingement of well fluid solid particles thereon.

The method according to this invention comprises producing well fluid from a well, establishing a confined conductive zone of known conductive state in the produced well fluid, monitoring the conductive zone to determine when the known conductive state is altered by solid particles encountering the conductive zone in quantities sufficient to physically affect that zone.

Accordingly, it is an object of this invention to provide a new and improved method and apparatus for producing a well. It is another object to provide a new and improved method and apparatus for monitoring fluid produced from a well. It is another object to provide a new and improved method and apparatus for controlling solid particle production from a well. It is another object to provide a new and improved method and apparatus for sensing sand production from a well.

Other aspects, objects, and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows apparatus employing one embodiment of this invention.

FIG. 2 shows apparatus employing another embodiment of this invention.

FIG. 3 shows a cross-sectional view of part of the apparatus of FIG. 2.

More specifically, FIG. 1 shows a well bore 1 in the earth 2 having production tubing 3 extending thereinto and being connected at the earths surface to a conventional wellhead 4. Wellheads are well-known in the art and therefore will not be described in detail except to say that wellhead 4 contains a master shut-off valve 5 and a pressure gauge 6 for determining the pressure of the produced well fluid. The well fluid passes upwardly through tubing 3 as shown by arrow 7 into production outlet pipe 8 which contains a conventional wing valve 9 and. choke 10, the produced well fluid passing through pipe 8, valve 9, choke 10 and onward for further treatment, transportation, storage, and the like, as desired as shown by arrow 11.

FIG. I shows a single completion well wherein all well fluid is produced through a single string of tubing 3 into a single outlet pipe 8. This invention applies equally to multiple completion wells wherein two or more separate strings of tubing 3 are connected to two or more pay zones, each string of tubing being connected to a separate outlet pipe 8 on wellhead 4. Thus, the number of strings of tubing 3 and the number of outlet pipes 8 can be equal to one another and also equal to the number of pay zones in which the well is completed. This invention applies to single or multiple completion wells and can be used on one outlet pipe 8, two or more outlet pipes 8 or all outlet pipes 8 as desired.

FIG. 1 shows an electrical wire 12 which passes through the interior of pipe 8 so that it is immersed in the well fluid being produced through that pipe. Wire 12 is carried by insulators 13 so as to electrically insulate wire 12 from pipe 8. Wire 12 is connected by way of wire 14 to an electrical source 15 which in turn is connected by wire 16 to a sensing means 17. The remaining end of wire 12 is connected by way of wire 18 to sensing means 17. Sensing means 17 is connected by way of electrical wire 19 to alarm means 20. Wire 12 can be carried in pipe 8 at any angle and pipe 8 itself can be at any angle as well as horizontal or vertical.

Source 15 which can be a battery, electrical generator, or the like, establishes electrical current through wire 12, source 15 having a known output and the magnitude of the current and/or voltage being known and recorded on sensing means 17. Means 17 can be a conventional voltmeter, ohmmeter, etc., with known readout and/or recording equipment. Thus, the magnitude of the electrical conductivity of wire 12 is established and known at a time when the well fluid being produced through pipe 8 contains substantially no solid particles.

Should the well fluid start producing solid particles in a substantial amount, the particles will impinge upon wire 12 and either physically erode it substantially or even completely sever the wire. When the wire is eroded, its resistance will go up which can be sensed by sensing means 17 since means 17 can also be an ohmmeter which will then indicate to the operator that there is a likelihood of solid particle production from the well. To attract the operator's attention, sensing means 17 can be set so as to actuate alarm 20 which, in this case, is simply a light 21, although any type of known alarm means can be employed. The sensing means 17 can also actuate well shutdown devices.

In a situation where the solid particles sever wire 12, the current as registered by sensing means 17 will drop to zero at which time alarm 20 can be actuated to indicate solid particle production in the well fluid and/or shut in the well through other devices.

FIG. 1 thus shows that embodiment of the invention when the conducting means is an electrical conductor and the means for establishing a known conductive state is an electrical source while the known conductive state is the present current or voltage applied to wire 12 before it is eroded or otherwise physically altered by solid particle impingement thereon. Wire 12 is also considered a confined conductive zone of a known conductive state since the electrical current and/or voltage applied is known before solid particles encounter electrical zone 12 in a quantity sufficient to physically affect that zone and thereby alter the conductive state, e.g., the electrical current magnitude, initially set up in zone 12.

FIG. 2 shows apparatus wherein the conductive means contains a fluid rather than electricity. In FIG. 2 the same wellhead and outlet pipe apparatus is shown but instead of conductor wire 12 there is a fluid conductor pipe which extends into or through the interior of pipe 8. Pipe 30 does not have to extend completely through pipe 8; it could just extend a closed end into the interior of pipe 8. The interior of pipe 30 is physically isolated from the interior of pipe 8 so that a pressure can be maintained in pipe 30 which is substantially different from the pressure of the produced well fluid in pipe 8. Conductor 30 is connected by way of pipe 31 to sensing means 32 while the opposite end of conductor 30 is connected by way of pipe 33 to means 32. Pipe 33 has a pipe 34 with valve 35 therein and is operably connected to pipe 33 to admit fluid as indicated by arrow 36 to the interior of pipes 30, 31, and 33 to establish a known conductive state in those pipes. Sensing means 32 is connected by way of wire 37 to an alarm means 38 which, in the case of FIG. 2, is a siren or horn, or to some other device which could shut-in the well.

The conductive state set up in conducting means 30 can be based upon a liquid, gas, or a combination thereof which is either constantly circulated through conductor 30 or statically maintained in conductor 30 as well as pipes 31 and 33.

Thus, should sufficient solid particles be produced through pipe 8 to erode a hole in conductor means 30 the interior of conductor 30 will be in communication with the interior of pipe 8 thereby effecting a change in the known conductive state of conductor 30. This change will be registered on sensing means 32 and will indicate solids particle production in the well fluid which, as with FIG. 1, in turn can actuate alarm 38.

The conductive state set up in conductor 30 can include a liquid which can be detected by suitable conventional monitoring means (not shown) established downstream from conduit 30 thereby indicating that solid particles have eroded a hole in conduit 30 and allowed the liquid in conducting means 30 to escape into pipe 8. Similarly, a vacuum can be imposed in conducting means 30 so that when a hole is eroded in conducting means 3%) well fluids can leak thereinto and can be sensed by sensing means 32 (in this case an analytical device) thereby indicating solids particle production through pipe 8.

Similarly, a gas can be employed in conductor means 30 and pipes 31 and 33, the gas being either at a pressure higher than the pressure of the well fluid produced in pipe 8 or lower than the pressure of the well fluid in pipe 8. In this situation when a hole is eroded in conductor 30 and the gas therein is at a pressure higher than the pressure in pipe 8, the known conductive state of high pressure for conductor means 30 will decrease which will be sensed by sensing means 32 and the alarm given. Along the same line, if the known conductive state of conductor means 30 is a gas at a lower pressure than that in pipe 8, the pressure in conductor means will rise when a hole is eroded therein by solid particles impinging thereon which will cause the pressure in conductor means 30 to rise which will also be sensed by sensing means 32 and the alarm given.

Of course, combinations of gas and liquid can be employed in conducting means 30 and combinations of electrical conductivity and fluid conductivity from FIGS. 1 and 2 can also be employed as desired.

FIG. 3 shows a cross-section of conductor 30 and pipes 31 and 33 in relation to pipe 8 and reveals that conductor means 30 is a confined zone passing through the interior of pipe 8 so that conductive means 30 is also considered a confined conductive zone of known conductive value. Thus, the conductive state can be a liquid which will be sensed downstream in pipe 8 if it leaks into that pipe, or a vacuum in conductor 30 into which well fluid could leak and be sensed, or a gas at a pressure higher than the well fluid in pipe 8, or a gas at a pressure lower than the well fluid in pipe 8, or any other variation wherein a similar type of known conductive state is established by means of a pipe, wire, or other type of conducting means (confined zone) which known conductive state will be affected when solid particles encounter the conductive means (zone) in quantities sufficient to physically affect that means or zone.

Although only one conductive means is shown in the apparatus of FIGS. 1 and 2, it should be understood that two or more conductive means can be employed in a single outlet pipe 8, the conductive means being carried at spaced apart points across and/or along the length of a section of pipe 8 so that more than one conductive means is employed in a particular pipe to give back-up protection and to serve as a double check capability. When more than one conductive means is employed in a single pipe, a sensing means can be employed for each conductive means or a common sensing means can be employed for two or more or all of the conductive means in a particular outlet pipe. Similar reasoning can apply to other outlet pipes carrying one or more conductor means even up to the point where a single sensing console is employed for all conducting means on one or more wellheads.

The conducting means are shown in FIGS. 1 and 2 to be located downstream of choke 10. This is a preferred embodiment, but this invention is applicable to the placement of one or more conductive means upstream of choke 10 as well as downstream of choke 10 or combinations thereof so that conductive means can be carried both upstream and downstream of choke 10. Conductive means can be carried upstream of valve 9 although it is better practice to keep valve 9 as close to wellhead 4 as possible from a safety point of view since this minimizes the number of connections between wellhead 4 and valve 9 thereby minimizing the number of potential leaks upstream of valve 9 which could necessitate the actuation of master valve 5. Thus, one or more conductive means can be employed anywhere in pipe 8.

The conductive means 12 and 30 can be bare in pipe 8 or can be coated or otherwise physically insulated to protect them from corrosion and the like.

The conductive means themselves can be fabricated of varying wire or wall thickness so that one is more resistant to solid particle erosion than another. When a plurality of conductive means are employed in a single pipe 8, one conductive means is more likely to wear out sooner than the other so that with a plurality of conductive means of greater and lesser resistance to solid par- ,ticle erosion, a quantitative estimate of the amount of solid particle production can be achieved. For example, wire 12 can be made of varying thicknesses and employed side by side across pipe 8 or along the length of pipe 8 so that if only slight sand production is encountered, only the thinnest wire '12 breaks whereas if an enormous amount of sand production is encountered all wires break and the operator is so apprised of the quantity of sand production he is suddenly faced with.

EXAMPLE Apparatus substantially the same as that shown in FIG. 1 is employed on a producing oil well wherein the well fluid comprises a mixture of liquid crude oil, liquid water, and natural gas. A single electrical wire 12 is em-- ployed and hooked to a voltmeter as sensing means 17. Electrical source 15 is conventional domestic electric outlet which imposes 1 l0 volts on wires l2, l4, and 16, the 110 volts being registered on voltmeter 17. A conventional low limit switch on voltmeter 17 is set so that should the voltage in wires 12, 14, and 16 decrease more than flve volts, alarm 20 will be triggered.

Thus, in the normal production of the well should sand start being produced in amounts sufficient to break wire 12, the voltage will decrease to zero at which time voltmeter 17 and its associated apparatus will actuate light 21 and warn the operator of sand production in the well so that he can take immediate remedial steps such as reducing the flow rate of the well to a value at which sand is no longer produced.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scopeof this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: r

1. Apparatus for determining whether solid particles are being produced from a well in the earth comprising a wellhead means, at least one production outlet pipe operably connected to said wellhead means, at least one fluid conducting means in the interior of at least one of said outlet pipes, means for establishing a known pressure state in said conducting means, and sensing means operably connected to said conducting means to sense any change in said known pressure state due to erosion of said conducting means by the impingement of solid particles thereon.

2. Apparatus according to claim 1 wherein said means for establishing said known pressure state is means for maintaining a known amount of fluid under known pressure conditions in said conducting means.

3. Apparatus according to claim 1 wherein said fluid conducting means carries a fluid at a pressure lower than the pressure in said outlet pipe.

4. Apparatus according to claim 3 wherein said fluid is a gas.

5. Apparatus according to claim 4 wherein said gas is air.

6. Apparatus according to claim 3 wherein said lower pressure is a vacuum.

7. Apparatus according to claim 1 wherein said flui conducting means carries a fluid at a pressure higher than the pressure in said outlet pipe.

8. Apparatus according to claim 7 wherein said fluid is a gas.

9. Apparatus according to claim 8 wherein said gas is air.

10. Apparatus according to claim 1 wherein there is an alarm means operably connected to said sensing means so that said alarm is actuated when said change in said known pressure state occurs.

11. A method for determining whether solid particles are being produced from a well comprising producing well fluid from said well, establishing a confined fluid conductive zone of known pressure state in saidproduced well fluid, monitoring the pressure in said conductive zone to determine when said known pressure state is altered by solid particles encountering said conductive zone in quantities sufficient to physically affect said conductive zone and cause a change in said known pressure state.

12. A method according to claim 11 wherein said solid particles are sand.

13. A method according to claim 11 wherein said conductive zone conducts a known fluid at a known pressure which is different from the pressure of said produced well fluid, and sensing when said known pressure changes due to said solid particles piercing said conductive zone so that the pressure in said conductive zone can equalize with the pressure of said well fluid.

14. A method according to claim 13 whereinsaid known pressure is less than the pressure of said produced well fluid.

15. A method according to claim 14 wherein said known fluid is a gas.

16. A method according to claim 15 wherein said gas IS an.

17. A method according to claim 14 wherein said lower pressure is a vacuum.

18. A method according to claim 13 wherein said known pressure is greater than the pressure of said produced well fluid.

19. A method according to claim 18 wherein said known fluid is a gas.

20. A method according to claim 19 wherein said gas lS air.

21. A method according to claim 11 wherein an alarm is activated when said known pressure state is altered. 

1. Apparatus for determining whether solid particles are being produced from a well in the earth comprising a wellhead means, at least one production outlet pipe operably connected to said wellhead means, at least one fluid conducting means in the interior of at least one of said outlet pipes, means for establishing a known pressure state in said conducting means, and sensing means operably connected to said conducting means to sense any change in said known pressure state due to erosion of said conducting means by the impingement of solid particles thereon.
 2. Apparatus according to claim 1 wherein said means for establishing said known pressure state is means for maintaining a known amount of fluid under known pressure conditions in said conducting means.
 3. Apparatus according to claim 1 wherein said fluid conducting means carries a fluid at a pressure lower than the pressure in said outlet pipe.
 4. Apparatus according to claim 3 wherein said fluid is a gas.
 5. Apparatus according to claim 4 wherein said gas is air.
 6. Apparatus according to claim 3 wherein said lower pressure is a vacuum.
 7. Apparatus according to claim 1 wherein said fluid conducting means carries a fluid at a pressure higher than the pressure in said outlet pipe.
 8. Apparatus according to claim 7 wherein said fluid is a gas.
 9. Apparatus according to claim 8 wherein said gas is air.
 10. Apparatus according to claim 1 wherein there is an alarm means operably connected to said sensing means so that said alarm is actuated when said change in said known pressure state occurs.
 11. A method for determining whether solid particles are being produced from a well comprising producing well fluid from said well, establishing a confined fluid conductive zone of known pressure state in said produced well fluid, monitoring the pressure in said conductive zone to determine when said known pressure state is altered by solid particles encountering said conductive zone in quantities sufficient to physically affect said conductive zone and cause a change in said known pressure state.
 12. A method according to claim 11 wherein said solid particles are sand.
 13. A method according to claim 11 wherein said conductive zone conducts a known fluid at a known pressure which is different from the pressure of said produced well fluid, and sensing when said known pressure changes due to said solid particles piercing said conductive zone so that the pressure in said conductive zone can equalize with the pressure of said well fluid.
 14. A method according to claim 13 wherein said known pressure is less than the pressure of said produced well fluid.
 15. A method according to claim 14 wherein said known fluid is a gas.
 16. A method according tO claim 15 wherein said gas is air.
 17. A method according to claim 14 wherein said lower pressure is a vacuum.
 18. A method according to claim 13 wherein said known pressure is greater than the pressure of said produced well fluid.
 19. A method according to claim 18 wherein said known fluid is a gas.
 20. A method according to claim 19 wherein said gas is air.
 21. A method according to claim 11 wherein an alarm is activated when said known pressure state is altered. 